Equilibrium in the Intake of Salts by Plant Cells. 451 



Table I. — Carrot in Potassium Chloride of different Concentrations. 



Time in 

 hours. 



Change in electrical condnctivity of external solution. 



Distilled 

 ^ater. 



Jf/oOOO. 



N/500. 



]S750. 1 



^710. 



0-5 

 6-0 

 24 

 52 -0 



+ 80 

 + 145 

 + 196 



+ 58 

 + 92 

 + 137 



- 3 



- 48 

 -196 

 -223 



-167 

 -372 

 -892 

 -992 



- 610 



- 970 

 -1600 

 - 1850 



Table II.— Carrot in Sodium Chloride of dififerent Concentrations. 



Time in 

 hours. 



Change in electrical conductivity of external solution. 



Distilled 

 water. 



i 



JS75000. i Jf/500. 



I 



N/50. 



X/10. 



3 

 34 -0 

 41 -5 

 48-0 



+ 36 

 + 87 

 + 66 

 + 58 



+ 30 j +18 

 4 57 i - 1 24 

 + 19 1 -287 

 + 2 j -340 



- 113 



- 476 



- 885 

 -1020 



- 560 

 -1070 

 -1580 

 -1720 



conductivity of the external solution.*. The quantity of such substances which 

 diffuses out of the cells is quite negligible in this regard. 

 (3) A decrea.se in exosmosis due to the action of the salt on the tissue. Even if the 

 extreme and unlikeh- assumption is made that exosmosis is reduced to nothing in 

 all cases, the results with carrot tissue would not in the main be affected. The 

 evidence available, however, from work on balanced solutions and the antago- 

 nistic action of ions, points in the other direction towards an increase in the rate 

 of exosmosis under the action of single salts. [See, for example. Stiles and 

 Jorgensen (11).] 



Possible causes rendering the values for the fall in conductivity of the external salt 

 solutions, as compared with distilled water, minimum values for absorption : — 



(1) An iDcreased exosmosis due to the action of the salts on the tissues. 



(2) An independent absorption of ions. It is quite clear that by the conductivity 



method we shall only be measuring the appioximate absoi-ption of the least 

 absorbed ion of a salt. When one ion of a salt enters the tissue in excess of the 

 other, its place must be taken in the external solution by some other ion, either 

 H, or OH (Pantanelli), or an iron escaping from the tissue (Meurer and 

 Nathansohn). Its excess ab.sorption will therefore not be measured. The extent 

 to which one ion may be absorbed in excess of the other is seen as the l esult of 

 the work of Nathansohn (8), Meurer (3), and Pantanelli (9). Moreover, owing to 

 differences in mobility of different ions, and changes in the degree of ionisation 

 resulting from replacement of one ion by another, the conductivity can only give 

 an approximate value of the abs6rption. 



